GH-48281: [Python] Remove skip in Numba-CUDA interop tests

- Numba-CUDA 0.21.2 has been released, which fixes the API breakage that
  affected Numba-CUDA interop tests.
- The previous commit fixes the installation of Numba-CUDA in the CI
  environment.
- This commit removes the skip of the Numba-CUDA interop tests, with the
  aim of them running again and passing.

Author: gmarkall

python/pyarrow/tests/test_cuda_numba_interop.py

@@ -22,9 +22,6 @@
 except ImportError:
     pytestmark = pytest.mark.numpy
 
-pytest.skip("Numba integration tests broken by Numba API changes, see GH-48265",
-            allow_module_level=True)
-
 dtypes = ['uint8', 'int16', 'float32']
 cuda = pytest.importorskip("pyarrow.cuda")
 nb_cuda = pytest.importorskip("numba.cuda")